Ingot



May 12 1942,

G. A. DoRN'lN INGOT Filed sept. 16,1941

'7 Sheets-Sheet 2 .WML

Tl Fim E 1 lNvEN'ro'R G eofgeA .D @Thin GIA. DORNIN INGOT May l2,` 1942.

Filed Sept. 16, 1941 1 '7 SheetS-SheefI 3 l INVENTOR y George/{.o/n/nMay 1 2. 1942.

DORNIN INGOT '7 sheets-Sheet 4 Filed Sept.- y16, 1941 m @mi www -INVENTOR v Geor ge 4. Dornin MM @M May 12, 1942.

G. A. DORNN 5 INGOT Filed sept. le, 1,941 '7 sheets-sheet 5 L 'nG71192241.1201min`1 l May l2, 19x42.

G. A. DORNIN NGoT Filed Sept. 16, 1941l 7 sheets-sheet e Patented May12, 1942 UNITED STATES PATENT oFEI'cE Applica::r;l enll):er:1: 410,982

7 claims.

This invention relates generally to an ingot of special configuration,whereby the amount of bottom croppage is materially reduced and to amold and mold stool for forming the ingot.

The present application is 'a continuation-inpart of my applicationsSerial Nos. 312,896, filed January 8, 1940; 350,841, led August 3, 1940;

363,305, filed Octoberf 29, 1940; and 397,062, led

June 7, 1941 Ingots of the prior art generallyA have been formed with aflat butt end substantially normal .to/ the axis of the ingot. It isknown that such ingots when rolled to reduce their section and elongatethem form fish tails which it is necessary to crop oil and, therefore,certain attempts have been made to shape the butt end of the ingot in amanner such as to overcome thisobjectionable feature. It has beenproposed, for example, in Patent No. 1,417,246, granted May 23, 1922, toB. P. Haziltine, to provide protuberances on the lbutt end of the ingot.According to that patent, the protuberance may be either cylindrical ormay be a .section of a sphere. Where the protuberance includes a sectionof a sphere, it is pointed out -jthat the curvature lof the protuberanceis made up of two radii, the radius of thecurvature adjacent the sidesof the ingot being greater than the radius adjacent the middle of theingot. In other words, the angle which the protuberance makes with theplane normal to the axis of the ingot and adjacent the periphery of theprotuberancey is less' than the angle between these elements as thecenter of the ingot is approached. yThe bottom -surface of theprotuberance forms with the plane normal to the axis of the ingot angleswhich increase from the peripheryv of the bottom surface toward itscenter.

Although the above mentioned patent and others have suggested the use ofa protuberance or convex bottom surface on the ingotfor the purpose ofpreventing fish tailing, none of them has taken into consideration otherequally important factors which are involved and which if not solved donot result in a. satisfactory ingot. I have found that it -is notsuilicient simply to provide a convex bottom-surface lon the ingot. 'lheconvex bottom surface must be of such convexity not only as to preventfish tailing, but as to prevent objectionable scabs on the bloom dueeither to rolling of the comers or to the rolling of ns produced at thecorners, due to the juncture of a mold and stool. 1f the angle betweenthe convex bottom surface and the side of the a material amount of thesurface on the bottom end of the rolled product and the discardnecessary is frequently greater than that caused by sh tail, thus notonly not curing the discard due to fish tail. but actually increasingthe loss. I have found, however, that by using the proper angles betweenthe convex bottom'surface and a plane normal to the axis of the ingot, Imay not only overcome any objectionable amount of fish tailing, but mayalso materially reduce the portion of the butt end of the ingot overwhich the objectionable scabs due to rolling down the corners or fins ofthe ingot will be formed. I may even limit the fish tailing and entirelyeliminate the formation of the just mentioned scabs. This angle betweenthe convexy bottom surface adjacent the sides of the ingot and a planenormal to the axisI call the critical angle. 'It is measured in a planeparallel to the axisand. normal tothe side of the ingot. It may decreasefrom the periphery of the convex bottom surface toward the center or thecritical angles of two opposing sides may be joined by a curvepreferably a radius.

In the accompanying drawings, ywhich illus- K Fig. 1 illustrates thediierent stages produced bry rolling an ingot having a flat bottomsurface, substantially a plane normal to the axis of the ingot.

Fig. 2 is a similar view, the ingot having a convex bottom surface inwhich the'angle be tween theconvex surface and the planenormal to thevaxis o f the ingot is too large to produce the desired results obtainedby my invention.

Fig. 3 is a similar view illustrating a correct angle between the convexsurface and the plane ingot is too great, these fins or, scabs willcover normal to the axisof the ingot.

Fig. 4 is a similar view illustrating the correct angle between theconvex bottom surface and the plane normal tolthe axis of the ingot, thecontour of the convex portion being made up of a series of anglesdecreasing toward the center.

' Fig. 5 is a vertical longitudinal section through an ingot mold and aningot mold stoolillustrating one form of my invention. 4- Y f Fig. 6 isa vertical longitudinal section taken on the line VI-VI of Fig. 5.

Fig. 7 is, a 'side elevation of the moldand stool shown in Fiss. 5 and6.

stool.

Fig. 8 is a plan view of the stool shown in Figs. 5 through 7. i Fig. 9is a perspective view of a removable wear plate which may be placed in arecess in the stool to prevent wear on the stool. Figs. 10 through 13illustrate a modified form y of the invention.

Fig. 10 is a side elevation of the modified ingot mold and ingot moldstool.

1 Fig. 11 is a vertical section taken on the line XI-IQ of Fig. 10.

Fig. 12 is a perspective view of the stool shown in Figs. l0and 11. y

Fig. 13 is a plan View of the stool shown in Figs. 10 through 12.

Fig. l4 is a vertical longitudinal section of the ence4 letter C and thehorizontal component by D. In reducing the ingot, the vertical tomponentreduces the section of the ingot and the horizontal component causes itto elongate. It will be seen that with a flat bottom ingot, whenthe rollapproaches the at bottom, there is no supporting metal below the atbottom at the portion marked I4 to counteract the horizontal componentD. Accordingly theA horizontal component D is eiective and causes aportion of the metal adjacent the surface to be elongated further thanthe metal at thel center, thereby producing the sh tail 9. The sh tailat this stage ofthe reduction 1s small but increases progreslower end ofan ingot mold and ingot mold stool illustrating a modied form of theinvention.

- Fig. 15 is a' diagrammatic plan view of the cavity portion of theingot mold stool shown in Fig. 12.

' Fig. 16 illustrates a series of vertical contours The reasons why theangle between the convex bottom surface and the plane normal to the axisofthe ingot must be maintained within certain critical limits will beunderstood from a consideration of Figs. 1 through 4. Each of thesefigures illustrate different stages in the reduction of an ingot 24"x,f24" section to a bloom approximately 8" x 8". The drawings representfour reduction steps in taking a 24" to an 8" secl tion, each steprepresenting a 4" reduction in the ingot the reduction being ordinarilyby two passes through the mill. The size of the ingot after the rstreduction step vis designated by the reference lnumeral 2, the sizeafter the second reduction by the reference numeral 3, the

size after the third reduction by the reference numeral 4, and the sizeafter the fourth reduction by the reference numeral 5. The rollingresults in the reduction of the ingot A to the sizeBand shape indicatedby the reference let- The ingot A has a flat bottom I which extendssubstantiallynormal to the axisVof the ingot. The manner in which fishtail is pro-v duced on the ingot is illustrated in Fig. .1. At

each rolling operation, a certain amount of fish tailing is produced,the amount of fish tailing increasing progressively as indicated by thereference numerals v9, IIL II and I2. Itwill be noted that the ingot Ahas a n I3, which was K formed at the juncture between the mold and Thisiin is first bent over and then continues to form a part of the fishtail,as illus- -trated in the drawings. as the ingot is reduced in'section. 'I'he formation of the fish tail .is be lieved to be caused forthe following reasons:

When an ingot is reduced by a rolling operation, the rolls exertpressure which -may be resolved into a vertical component extendingsively during the succeeding reducing operations, as indicated by thereference numerals I0, I I and I2, so that when the ingot A has beenreduced to the bloom B, there is a very substantial amount of the bottomportion of the bloom which is sh tailed and which it is necessary tocrop 0E. It will be noted that the ilsh tail exvtends from the end ofthe bloom back to the point I5. The linewhere it is necessary to cropoif the bloom is indicated by IQ. The amount of metal necessary to cropoi'f variesbut is` generally about 4% of the total weight of the ingot.

It will be noted that the iin I3 always remains at the apex of the ii'shtail 9'-'I2 and that the sh tails and the fin move from the plane of thebottom surface of the iingot A progressively lengthwise of the bloomnB.At the end of the rolling operation, it is located at the extreme end ofthe fish tail and the fish tail is consider'- ably below the bottomofthe original ingot A.

Referring now to Fig. 2, the'ingot E instead of having a flat bottom isformed with a convex bottom formed by the ilat surfaces I0- and I9,which converge. to the point 20. The surface I8 makes an angle with thedot and dash line 2| drawn normal to theE axis of the ingot'E of aboutThe angle of 60, although being satisfactory from the standpoint ofpreventing sh tailing of the ingot, is unsatisfactory because it resultsinthe formation of scabs or fins over a large portion. of the bottom endof the ingot. As in the case of Fig. 1, the rolling pressure may beresolved into Aa vertical component C and a horizontal component D. InFig. 2, however,

since the bottom of the ingot has a convex sur-4 face, there is aportionof metal extending below .the line 2| which counteracts the horizontalcomponent. D.' This section of metal is indicated by kshading and'designated by the reference numeral 22. It acts asa support, whichcounteracts the horizontal component D and prevents the horizontalcomponent from forming any iish tail on the ingot. It will be ynotedthat as the ingot is reduced in section the n I3 does not movedownwardly but always remains with its upper end in the plane of theline 2l. However,

it is elongated with each reduction. Since the section 22 of supportingmetal entirely counter acts any tendency ofthe horizontal component toform iish tail on 'the ingot, the only eifective pressure is thevertical'component Cand'this merely causes the base of the iin II toremain stationary while'it is elongated.' Thus when the ingot E has beenreduced to the 'bloom F, the fins or the scabs resulting from rollingthem or the corners of the ingot, still extend backwardly along theingot to the line 2| and it is necessary normal to the sides of theingot and a horizontal component extending longitudinally of the ingot.The vertical component is indicated by thereierto crop on.' atapproximately the line 23. 'I'his croppage in thefexamples shown amountsto approximately of the totall weight of the ingot and is 50% more thanthe croppage for a normal fish tail as shown in Fig. 1. Thus, althoughthe problem of fish tailing has been overcome by providing the bottom`of the ingot.with a convex surface, this has introduced another problemwhich is even -more disadvantageous than the production of iish tailsitself.

InFig. 3, the ingot G is provided with a convex bottom surface whichforms an angle of about 24 with the line 26 which is normal to the axisofthe ingot. The two surfaces 25 are joined by a hat bottom surface 2l.This angle of 24 is a proper angle to use in accordance with myinvention, but as will be explained later on incon-- nection with Fig.4, it is preferred to form the convex surface of at least 4 surfacesextending at an angle to thesides of the ingot and to connect theseangled surfaces by a fiat bottom surface. I'he angle H, whichisapproximately-24,

provides a supporting body of metal which has I embodiments illustrated,each reducing step reduces Ithe section about 4". As the! reducing beenshaded and is designated by I. Iny this case4 also, the verticalcomponent of the roll pressure is indicated by C and the horizontalcomponent by D.A The body I'of supporting metal is sumcient so thatalthough it prevents fish tailing it issomewhat less than would berequired to entirely counteract the horizontal component 1D. v

Asa result, the horizontal component D is effective to a certain extentand causes the base 28 of the ln I3 to move progressively to the points23,30, 3| and 32 as the rolling progresses. In this way, the n'insteadof remaining with its` base in the plane of the line 26 moves toward thebottom end of the ingot, so that when the ingot G has been reduced tothe bloom K the fin is located nevar the bottom end of the bloom, asindi-A cated by the reference numeral 32. Accordingly it is necessary tocrop ci only a much less amount of the bloom than was the case of thebloom produced in accordance with Fig. 2. The bloom may be cropped atthe line 33.

In Fig. 3,-it will be noted that the surfacev 21 is flat andsubstantially normal to the axis of the ingot. When the ingot G hasbeen'reduced down to the size indicated by the reference numeral I, wethen have in effect a flat'bottomed ingot and further reduction resultsin sh tailing of a character somewhat similar to that shown in Fig. 1.The character of the flsli tailing is modied by the fact that in,reducing the ingot I to the .bloom 5 a large percentage reduction ismade. This heavy reduction has the efwith Fig; 3. That is, thesupporting metal ad-' jacent the apex of the angle P is insu'lcient tocounteract vall of the horizontal component D of the rolling pressureand accordingly the base-of` the fin I3 moves lengthwise of the ingot tothe positions 40 and 4I. It will be noted that in the steps progress,the percentage of reduction for each step, therefore, increases. As theApercentage of reduction increases, 'the tendency to vfish tail becomesless and the tendency'to form a bulb on the end of the ingot increases.For example, if a press were used instead of a roll and the ingot beingreduced had a at bottom,A the reduced product would have a bulb on itsend instead of a fish tail. That is. as the percentage of reduction isincreased, .the tendency to fish tail is decreased, the tendency to forma bulb on the.

end of the ingot is increased and the eiectof the horizontal component Ddecreases. As shown in Fig. 4, I may crop the bloom approxi`- y matelyat the line 43, so that the croppage amounts to only about 1% of theingot weight.

vIt will be seen that the angleP shown in Fig. 4 I

`must be maintained Within certain limits, in order to produce thedesired results. Ifthe angle is too small, the ingot will fish tail. Onthe other hand, if it is too large, it will result in the iin or cornersimply traveling inwardly toward the center of the ingot without movingprogressively lengthwise thereof as the reduction proceeds, and it willbe necessary to crop olf a large amount of the ingot. In reducing a`24ingot by percentf ages'such as are common in commercial practice today,I prefer to make the angle P about 24 and the angle Q about 12. Theseangles will vary according to the initial size of the ingot f and thepercentage. of reduction/in the various passes. If the initial ingotsection is less :than

214 or the percentage of reduction per pass iS greater in proportionvthan commonly employed)` I would reduce the angle Pand the angle Q.

` On the other hand, if the initial ingot was greater than 24", .or ifthe reduction 'per'pass was f fectof bulging the end of the bloom, sothat it takes the shape indicated by the reference numeral 34. In ordertc further decrease this tendency to fish tail or to bulge after thereduction has been carried out to a certain extent, I preferably employa convex bottom surface on. the inl got of the shape illustrated ifiFig. 4.

Referring now to Fig. 4, the ingot M is reduced to the bloom O in amanner similar to that 'pre,

surfaces 36 and the line 38 is approximately 12. I may: use anynumber'of surfaces to make up theconvex shape of the bottom end of theingotl Y and in those cases where a very large number of ness of vtheingot which is to be reduced.

less than commonly used in commercial practice,

I would increase .the angles P and Q. When the' convex` surface is madeup of two surfaces such'as 8S and 36 extending at angles to the lined!-ns shown in Fig. 4, the angle Q should be approximately one-half theangle P. Where there are three surfaces between 'a side of ythe ingotand the surface=at the center of the ingot which is normal 'tothe axisof the ingot, the

other, angles Q should be-'about two-thirds ofy P, one-third of P,respectively, and so on.

I have found that the critical angle P which should be used bears arelationship to the, thick- From extensiveexperiments which I havecarried out on a very largetonnage of ingots', I have 4found that thecritical angle as-expressed in degrees should be approximately equal tothe thickness x as expressed in inches of the bottom end of the ingot.Thus, as previously mentioned, in a J .24" x 24"' ingot, the criticalangle is preferably labout' 24.

In a like manner, in a 24" x 36" ingot, the critical angle is preferablyabout 24. In an 18" x 25" ingot, it is preferably about critical angle.

l should not'be less than about 19. In a similar provided by the moldand the mold stool.

18. Itfollows that the critical angles will vary according to theinitial thickness of the ingot, 4but there should always be the properrelationship between theithicknessof the ingot and the r l The criticalangle need not be exactly equal to the thickness of the ingot but needbe only approximately so. Furthermore, it is the thickness of the `ingotat the bottom of the ingot which is to be considered, irrespective ofwhether the ingot vis big end d own or big end up. In carrying out myinvention, the critical angle as expressed in degrees is generally equalto the thickness of thev bottom end of the ingot as expressedin inches.plus or minus about Referring to Fig. 19, the'relationship between thecritical angle and the thicknessv of the bottom end of the ingot isshown. As shown in this figure, the preferred critical angle for ingotsof different thicknesses is represented by the line |20. It will benoted, for example; that an ingot which is 24" thick at the bottompreferably has a critical angle of 24. -Since this preferred criticalangle may vary somewhat according to particular conditions, such aspercentage of reducg5 tion per pass, I have represented by the area |2|,enclosed by the parallelosram, |22, the approximatelypermissible'variations in critical ansies for ingcts of variousthicknesses. I .have `found th-at generally the critical angle as exp din degrees should not be more than about 5 eatennor less than about-5less, than the thickness vof the bottom of the ingot as expressed ininches. This permissible variation is represented by the paralielogram|22, which includes 35 ingots of different sizes having thicknesses of17 to As shown by the enclosed area |2I, the critical angle for an ingothaving a thickness of 24" should not begreater than about 29 and- 40`manner, an ingot which is l'1'-' thick should have a critical angle notgreater than22',nor.less than 12 and in an ingot having a thickness of35" the critical angle should not exceedabout 40 and should not be lessthan about 30. 45

' Referring now nore particularly to the accompanying drawings andforthe present to Figs. 5 through 9, which illustrate one form of the'invention, an ingot' mold 48 and aningot mold stool 49 are shown. Theingot issquare in cross 50 section and tapers slightly from the bottomto the top. The ingot'may. however, be of other shape than square: Itmay have two broad sides and ytwo narrower. sides, particularly inthose. rcases where the ingot is to be rolled into slabs. 'Ihe mold `isprovided with the 4usual lugs B0 for raising the mold after the ingothas been cast. 'I'he ingot has `not been shown in the moldl but ofcourse will be of the contourk of the cavity Referring to Fig.-5,the-stool 'is' provided with .a cavity indicated generally by thereference numeral 5|, which forms a convex bottom surface on thein'got.In order toprevent wear on the `65 ,surface of the stool, itis providedwith a recess 52 which receives a removable wear plate 53 illustrated inFig'. 9. When the ingot is cast, the wear plate sticks to the end of theingot but is knocked off duringhandling or rolling or is cutoff with thebottom erop and another wear plate is placed in the recess in the stoolbefore another ingot is cast. l-The present-inven- 'tion relatesparticularly to the shape of the con- `vex bottom, surface'formed on thebutt 'end 0f 7 5 thelngot and is applicable whether or not rmovable wearplates'are provided for the stool. As shown particularly in Figs. 5 and8, the

cavity 5l in the stool is formed of flat surfaces 54' and 55, whichextend at an angle to the plane 5t normal to the axis of the ingot. Thetwo surfaces 55 are connected by a flat surface 51, which is normal tothe axis lof the ingot. y"I'he angle P between the surface I4 and theplane 58 normal to the axis of the ingot is approximately 24. The angleQ between thesurfaee 5 5 and the plane normal to the axis of the ingotis approximately 12-that is, about one-half of the angle P.

The cavity 5| in the stool is rectangular in,

shape, having two long Asides 5I and two short sides CII, as shown inFig. 8. The two opposite sides 6| of the mold are each formed with a vdownwardly extending projection 82,- as shown in Fig. 5, whichprojections are located intermediate the corners of the mold. 'I'heseprojections -62 havetheir lower surfaces conformingto the shape of thecavity in the stool, so that the sides 6I of the mold iit into thecavity and preventI displacement of the mold and stool in one direction.At each end of the stool is`a flange 63,

which acts to center the mold on the stool in the other direction.' z Asshown in Fig.'8, the cavity in the stool is surrounded by a border madeup of two flanges Il at the ends andtwo ilat surfaces 64 at the sides.lThe sides 58 ofthe mold have flat bottom surfaces I5, which aresupported on Y the ilat portion I4 of the stool. Thus the two .oppositesides it of the mold rest on the broader portion 84 of the stool whilethe projections l2 at thel lower ends of the sides'il of the mold fitinto the cavity Il in the stool.

Referring now to theembodiment illustrated in Figs. 10 through 13, amold l! is supported on a stool 1|I`. The mold has four sides 1T, eachof the sides being of the same configuration. 'I'he bottom edge of eachside of the mold is formed witha projection 12 made up of the surfaces13,

14 and-1l, this projection being located intel'- medlate the corners 'ilof the mold. The surfaces 13, 14 and 15 of the mold conform respectivelyto the surfaces 12', 1 4' andI 15 -in the border of the stool. Thecorners 16 of the mold rest on thecorners 18 of the stool.

The cavity 11, which forms the convex bottom on the ingot, is so shaped`that the bottom ofthe ingot is'convex in shape when viewed from anyThis type of ingot and mold is pref- -f of its sides. erably used wherethe ingot is to be reduced materially both in thickness and Width;whereas the ingot produced in themolds shown in Figs. 5

through 8 is intended primarily for use where most of the reduction isto be performed on-two sidesl of theingot `and only afrelatively smallamount of reduction is performedon the other two sides. The ingotmold/is provided with lifting lugs -8|! 'and with a removable wear plateIl.

Cavity" in the stool is formed by the surfaces l2 and u, which'v extendat angles Vto the sides 69a of the mold.v The surfaces are joined by afiat surface I4. The surface I2 makes `an angle R. of 24' with the planenormal to the axis of the ingot. The surface 83 makes a smallthe planenormal to the axis than does the surfaces 82.

The cavity 11 also has the surfaces #I8 and I6 extending at angles tothehorizontal, the surfaces 86 being joined `by aflat surface 81 extendingnormal to the axis ofthe ingot.l 'I'he surface l5 makes an angles of 24with the plane normal tjsurface 86 makesv through 8 has a convex bottomsurface when thesection is taken in a plane extending through two sidesof the ingot. When the section is taken in a plane through the other twosides of the ingot, thebottom surface isa straight line. This typeof-ingot is particularly useful where most of the reduction is to beperformed on the two sides y of the ingot which are joined by the convexsurface, such as in producing slabs from ingots having two broad sidesand two narrow sides.

The ingot produced in the mold shown in Figs. 10 through 13 has a convexbottom surface in a plane through two sides of the `ingot and also aconvex bottom surface in a plane taken through the other two sides ofthe ingot. This type of ingot having a compound convexity is particu--larly useful Where the ingot is to be reduced to a materially smallersection in both directions by working upon all four sides of the ingot.

In the embodiments thus far described (see Figs. and 11) the cavity inthe mold stool which forms the convex bottom surface on the ingot isco-extensive with the cross-sectional area of the mold where it seats onthe mold stool. In other of Fig. 16 represent the contours taken alongthe corresponding section lines of Fig.15. The surface |00 has thesameinclination to the horizontal, i. e., the same inclination to the planenormal to the axis ofthe mold, whether the section through the stool betaken-through the center of the stool, as indicated through an edge ofthe moldcavity, as indicated 'by the line A-A, or through any-intermediate section. Thus in Fig. 16 all of the angles |0|, |02, |03,|04 and |05 are 24".- In a similar manner, kthe contour linesrepresenting sections taken at right angles to the sections A-A, B-B,C-C.. the same inclination toy D-D and E-E all have lthe horizontal.This arrangement is satisfactory where the ingot-is to be rolled betweencylindrical rolls. Where, however, the ingot `is to be.

' rolled extensively through collared passes, it is words,l as shown inFig. 5, the outer edge of sury face 54 of the mold cavity lies flushwith the wall 56 of the mold. It is not necessary, however, in all casesthat the cavity in the stool be co-extensive with the area of the ingotmold. I may, for

example, employ the present invention in corinection with a mold andstool as shown in Fig. 14. In this embodiment, the width 90 of thecavity in the mold is greater than the width 9|- of the cavity in thestool, so that there' is a ledge 92 on the stool. The cavity in thestool is formed by a series of surfaces 93, 94 and 95 similarrespectively to the surfaces 81, 86 and 85 yshown in` Fig. 11. Thesurfaces95 form anglesof 24 with the plane normal to the 'axis of theingot mold. In referring in the claims to "the bottom surface adjacentthe sides of the 'ingot, it is intended to include not only anarrangement such asshown in Fig. 5, in which the outer edge of thesurface 54 lies us'h with the inside wall 56` of the mold-i. e., flushwith theside of the ingot-but also an ingot produced in an apparatussuch as shown in Fig. 14. In Fig. 14, the surface 95 is spaced from theinside wall 96 of the ingot mold by the width of the ledge 92. An ingotproduced in this apparatus will have a ledge corre sponding to the ledge92 between the sides. of the ingot and the convex bottom portion of thelingot.

Although it is preferred inl most casesto have the outer edge of thesurface 95 flush with the surface 9B, some of the benetsof my inventionmaybe obtained in a construction such as shown in Fig. 14. 'I'he ledge92 ordinarily should not be over about 1" or 2" in width, because if theledge is made-wider than this, there is danger of theY ingotiish-tailing in rolling. I might, for example, use a 20" mold stool witheither a 2,0" mold or a 22" mold. In the former case, the outer edges ofthe surfaces 95 would lie ilushwith the inner wall of the mold, whereasin the latter case there would be a ledge such as the ledge indicated bythereference numeral 92. j

In the mold stool shown in Fig. 12, vertical sections taken parallel tothe sides of -the stool at the center of the stool and at variousdistances from the center all will have the same contour. This isindicated in Figs. and 16 in which the preferred that the anglerwhichvthe surface of thecavity -adjacent the sides of the ingot mold makeswith the horizontal be less atand adjacent the corners of 'the ingotthan it is at and adjacent the middle of the sides of the convex end ofthe iny got. `Such an arrangement isillustrated in Figs.

17 and 18. As here shown, the contour line E-E which represents asectionthrough the middle an angle ||0 of about 24` of the lngot makes with thehorizontal.. C-C, B-,B and A-,A tively ill, H2, ||3 and I The contourlines D'D,

I4 of 23, 2030", 20'and I'he critical angle between thesurface of thecavity and` the plane normal to the axis of the ingot may be the same atthe middle of the sides of the ingot and at thecorners of the-ingot andat all points therebetween, as shown in Figs. l2 and 16; or the anglemay decrease from the middle of the sides of the ingot toward thecorners, as shown in Fig. 18. 'It is essential according to the presentinvention that the critical anglefb/e used at the middle of the side ofthe ingot. In certain cases, it is desirable that the critical angle beused throughout a majorportionof the whole ingot section.

The invention is not limited to the preferred.

embodiments, which have been given merely by way of example, but may beotherwise embodied of the following Y f or practiced within the scopeclaims.

I claim:

1. An ingot havinga convex bottom surface,

parallel to the axis of the ingt and normal to 1 n said sides of theingot. being approximately equal to the thickness, as expressedv ininches,` of the bottom end of the ingot.

2. An ingot having a convex bottom surface,

i each of the angles between the convex bottom surface adjacent'thesides of the ingot which define the thickness of the ingot and the planenormali-.o the axis ofthe ingot, a-sexpressed-in degrees, when s aidangle n parallel to the axis of the ingot and normal to said sides oftheingot,y being equal to the thickness, as expressed in inches, plus orminus 5, of the bottom end of. the ingot.

3. An ingot having a convex bottom surface is measured in a' plane and athickness not less thanabout 17." and not f I more than about each oftheangles between the convex bottom surface adjacent thesides' of i5contour unes A-A, B-B, o o, n n and E-E by the line E-E, or

make the angles respecthe inzot which deiiner the thickness of the insotand the plane normal to the axis oi.' the ingot, as expressed indegrees, when said angle is measf ured -in a plane parallel to the axisof the ingot i and normal t said sides of the insot, being equal to thethickness, as expressed in inches, plus or minus of the bottom of theingot.

in a plane parallel to the axis of the ingot and normal to said sides ofthe ingot, being equal to the thickness, as expressed in inches, plusor` minus 5, of the bottom end oi' the ingot.

the thickness. as expressed in inches, plus or minus 5, o! the bottomend or the ingot.

6. Aningot having a' convex bottom surface, each of the angles betweenthe convex bottom 1 ysurface adjacent the middle oi the sides of theinzet which denne the thickness o! the insot and the piane normal to the`axis of the lngot. as expressed in degrees, when said -angle ismeasured in a plane parallel to the axis or the ingot and normalto'saidsides of the insot, being equal to the thickness,v as expressed ininches, plus or minus 5, -of the bottom end of the ingot, these anglesdecreasing toward the corners.

'7. An ingot having a convex bottom surface, each of the angles betweenthe major portion of the bottom surface adjacent the sides of the in- 5.An ingot having a convex bottom surface,

each of the angles between vthe convex bottom surface adjacent themiddle `of -the sides 6! the ingot which define the thickness of theingot and the plane normal to the axis of the ingot, as expressed indegrees,` whenfsaid angle is measured in a plane parallel to the axis ofthe insot and normal to said sides of theinsot, being equal to got whichdenne the thickness of the ingot and the plane normal to the axis of theingot, as exI pressed in degrees, when said angle is measured in aplaneparallel in the axis of the ingot and normalto said sides of theingot, being equal to the thicknesseas expressed in inches, plus or cminus 5, of the bottom end of the ingot.

f GEORGE A. DORNIN.

